BACKGROUND OF THE INVENTION
[0001] This invention relates to methods, compositions and kits for detecting the presence
and/or amounts of amphetamine and/or methamphetamine in samples suspected of containing
the same. In particular, the invention relates to bivalent hapten conjugates comprising
an amphetamine moiety and a methamphetamine moiety. The conjugate may be employed
in assays for amphetamine and/or methamphetamine.
[0002] The clinical diagnostic field has seen a broad expansion in recent years, both as
to the variety of materials of interest that may be readily and accurately determined,
as well as the methods for the determination. Over the last decade, testing for drugs
of abuse has become commonplace. This testing is not only for the monitoring of criminal
offenders and drug addicts, but employers also use it for the screening of workers.
In recent years, immunoassays based on the reaction of an antibody with an antigen
have been extensively investigated for this purpose.
[0003] Typically, immunoassays employ an antibody whose structure recognizes an analyte
in a specific manner. The immunoassay is conducted with a signal producing system
that produces a detectible change in signal upon binding of the analyte to the antibody.
Accordingly, when testing for an analyte in a sample, a detectible change in signal
from that produced with a negative sample of a calibrator is taken as a positive result
for the presence of that analyte in the sample.
[0004] Amphetamine and methamphetamine stimulate the central nervous system and have been
used medicinally to treat hypotension, narcolepsy and obesity. Because of their stimulating
effects, the drugs and derivatives have been abused. As a result, assays for the detection
of amphetamine and/or methamphetamine in samples are of interest.
[0005] There is a problem when the aforementioned assay techniques are employed to assay
for amphetamines in a sample suspected of containing amphetamine and/or methamphetamine.
The problem arises because these assays employ a single antiserum or antibody that
can recognize both amphetamine and methamphetamine. In order for this antibody to
recognize both amphetamine and methamphetamine, it is necessary for it to be capable
of recognizing a particular spatial and polar organization common to amphetamine and
methamphetamine and to lack specific recognition of those structural features of amphetamine
and methamphetamine that are different. Because such an antibody recognizes structural
features that are common to both of these compounds but lacks specific recognition
of the structural features that are different, it is able to recognize both compounds
and the assay will produce a positive result for a sample containing amphetamine and/or
methamphetamine. However, antibodies that recognize both compounds have been found
to recognize molecules other than amphetamine and methamphetamine that share some
but not all of the common spatial and polar features of amphetamine and methamphetamine.
[0006] The above problem was solved in
U.S. Patent Nos. 5,135,863 and
5,328,828 (Hu, et al.), which disclose an immunoassay to determine the presence of amphetamines in a sample
suspected of containing amphetamine and/or methamphetamine by employing four primary
reagents. Two of these reagents are two conjugates, each comprised of a functionally
similar label bound to an amphetamine analog and a methamphetamine analog, respectively.
The other two reagents are an antibody to amphetamine and an antibody to methamphetamine.
[0007] There is, however, a need for assays for the detection of amphetamine and/or methamphetamine
where the number of reagents employed is reduced from that mentioned above and the
assay maintains the same level of sensitivity, specificity, speed and accuracy as
the assay disclosed in
U.S. Patent Nos. 5,135,863 and
5,328,828 utilizing four reagents.
SUMMARY OF THE INVENTION
[0008] One embodiment of the present Invention is a compound of the formula:

wherein:
R1 is hydrogen or a protecting group,
R2 is hydrogen, lower alkyl, or a protecting group,
L1 is a linking group,
Y1 is a bond, a functional group or a linking group and is bonded to L1 at a point equidistant between the point of attachment to each of the phenyl groups,
Z1 is a poly(amino acid), a non-poly(amino acid) label or a functional group; and
t' is 1 when Z1 is a functional group or a non-poly(amino acid) label or, when Z1 is a poly(amino acid), t' is an integer between 1 and the molecular weight of a poly(amino
acid) divided by about 500;
and salts thereof.
[0009] Another embodiment of the present Invention is a compound of the formula:

wherein:
R1 and R2 are independently H or a protecting group,
X and X' are independently O, S, or a bond;
D and D' are independently alkylene or substituted alkylene;
V and V' are independently O, S, or a bon;
W is CH;
Y is NR3 wherein R3 is H or lower alkyl, O, S, or a bond;
T is alkylene, -(C=O)alkylene, ethereal alkylene, acetamide or a bond;
Y' is NR3 wherein R3 is H or lower alkyl, O, S, or a bond;
T' is alkylene, -(C=O)alkylene, ethereal alkylene, acetamide or a bond; and
Z' is a poly(amino acid), a non-poly(amino acid) label moiety, H, Br, Cl, F, I, NH2, acetamide, haloacetamide;
t" is 1 when Z' Is a functional group or a non-poly(amino acid) label or, when Z'
is a poly(amino acid), t" is an integer between 1 and the molecular weight of a poly(amino
acid) divided by about 500;
with the proviso that X and X' have approximately the same length, D and D' have approximately
the same length, and V and V' have approximately the same length; and salts thereof.
[0010] Another embodiment of the present invention is a compound of the formula:

wherein:
R1' and R2 are independently H or a protecting group, X1' and X1" are S or O;
Z" is an enzyme; H, Br, Cl, F, I, NH2, acetamide, haloacetamide;
t"' is 1 when Z" is other than an enzyme and, when Z" is an enzyme, t"' is an integer
between 1 and the molecular weight of the enzyme divided by about 500; and
n, m, p, q, r and s are each independently 0 to 5;
and salts thereof.
[0011] Another embodiment of the present invention is a compound of the formula:

wherein:
Z" is an enzyme; and
t"' is an integer between 1 and the molecular weight of the enzyme divided by about
500.
[0012] Another embodiment of the present invention is a reagent system comprising a compound
of Formula V (wherein the compound comprises an enzyme label), an antibody for amphetamine
and an antibody for methamphetamine.
[0013] Another embodiment of the present invention is a method for determining amphetamine
and/or methamphetamine in a sample suspected of containing amphetamine and/or methamphetamine.
A combination is provided in a medium where the combination comprises the sample and
the aforementioned reagent system. The medium is examined for the presence of a complex
comprising the compound of Formula V (wherein the compound comprises an enzyme label)
and the antibody for amphetamine and the antibody for methamphetamine. The presence
of such complexes indicates the presence of the amphetamine and/or methamphetamine
in the sample.
[0014] Another embodiment of the present invention is a method for determining amphetamine
and/or methamphetamine in a sample suspected of containing amphetamine and/or methamphetamine.
A combination is provided in a medium where the combination comprises (i) the sample,
(ii) an antibody for amphetamine, (iii) an antibody for methamphetamine, and (iv)
a compound of Formula III, which comprises an enzyme and wherein R
1' and R
2' are H. The medium is examined for the presence of a complex comprising the compound
of Formula III and the antibody for amphetamine or the antibody for methamphetamine.
In one approach, the complex is detected by means of the enzyme. The presence of such
complexes indicates the presence of the amphetamine and/or methamphetamine in the
sample.
[0015] Another embodiment of the present invention is a method for determining amphetamine
and/or methamphetamine in a sample suspected of containing amphetamine and/or methamphetamine.
A combination is provided in a medium where the combination comprises (i) the sample,
(ii) an antibody for amphetamine, (iii) an antibody for methamphetamine, and (iv)
a compound of Formula IV, which comprises an enzyme and wherein R
1' and R
2' are H. The medium is examined, usually by determining enzyme activity, for the presence
of a complex comprising the compound and the antibody for amphetamine or a complex
comprising the compound and the antibody for methamphetamine. The presence of the
complexes indicates the presence of the amphetamine and/or methamphetamine in the
sample.
[0016] Another embodiment of the present invention is a kit comprising in packaged combination
(i) an antibody for amphetamine, (ii) an antibody for methamphetamine, and (iii) a
compound of Formula IV wherein the compound comprises an enzyme and R
1' and R
2' are H.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a reaction scheme depicting an example of a synthesis of certain compounds
in accordance with the present invention.
[0018] Figure 2 is a reaction scheme depicting an example of a synthesis of certain compounds
in accordance with the present invention.
[0019] Figure 3 is a graph depicting the inhibition of enzyme bivalent hapten conjugate
by amphetamine and methamphetamine antibodies.
[0020] Figure 4 is a graph depicting a standard curve for amphetamine with an enzyme bivalent
hapten conjugate in accordance with the present invention.
[0021] Figure 5 is a graph depicting a standard curve for detection of methamphetamine with
an enzyme bivalent hapten conjugate in accordance with the present invention.
[0022] Figure 6 is a graph depicting results of the detection of amphetamine and methamphetamine
in a three-component system
[0023] Figure 7 is a reaction scheme depicting an example of a synthesis of certain compounds
used in the synthesis of compounds in accordance with the present invention.
[0024] Figure 8 is a reaction scheme depicting an example of a synthesis of certain compounds
used in the synthesis of compounds in accordance with the present invention.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0025] The present invention permits effective screening of samples for the presence of
an amphetamine or a methamphetamine using a smaller number of reagents than that employed
in the methods of
U.S. Patent Nos. 5,135,863 and
5,328,828. The methods utilizing the compounds of the invention achieve substantially the same
level of sensitivity, specificity, accuracy and speed as the known method.
[0026] The assay compositions comprising the compounds of this invention are useful in a
wide variety of previously employed assay methods such as, e.g., immunoassay methods,
both homogeneous and heterogeneous. The conditions under which these assays have been
carried out will normally be applicable to assays employing the present compounds.
Thus, the compositions can be used in prior art immunoassays so as to provide a means
to determine the presence of amphetamine and/or methamphetamine in a sample suspected
of containing amphetamine and/or methamphetamine. By appropriate choice of components
for producing a detectible signal, the detectible signal may be observed visually
or by means of various apparatus, i.e., detection means, such as spectrophotometers,
fluorometers, scintillation counters, etc.
[0027] The assay composition includes the present compounds comprising a label and also
includes ancillary reagents necessary to produce a signal from the present compounds.
A key reagent in the signal producing system is a single conjugate comprising an amphetamine
moiety and a methamphetamine moiety linked together and further linked to a label,
either a poly(amino acid) such as an enzyme or a non-poly(amino acid) such as a fluorescent
compound. The choice of assay or assay protocol usually determines whether an increase
or decrease in the amount of signal generated by the signal producing system determines
the amount of amphetamines in the assay sample.
[0028] In the present invention, a three-component reagent system according to claim 7 is
employed.
The reagent system may be used in methods for detecting the aforementioned drugs in
samples suspected of containing the drugs. In the assays the amphetamines, i.e., amphetamine
and methamphetamine, to be measured are the analytes. In general, an analyte is a
ligand and is a member of a specific binding pair, which may be, for example, the
ligand or analyte and a corresponding antibody for the ligand or analyte.
[0029] Suitable types of protecting groups are well known in the art and have been described
in detail in numerous patents and articles in the technical literature. See, for example,
"
Principles of Peptide Synthesis" (M. Bodanszky, Springer Verlag, Berlin, Heidelberg,
New York, Tokyo (1984). Such protecting groups include, by way of example and not limitation, t-butoxycarbonyl
(t-Boc), fluorenylmethyloxycarbonyl (Fmoc), acetaminomethyl (Acm), triphenyl methyl
(Trt), benzyloxycarbonyl, biphenylisopropyloxycarbonyl, 1-amyloxycarbonyl, isobornyl-oxycarbonyl,
alpha-dimethyl-3,5-dimethoxybenxyloxycarbonyl, o-nitrophenylsulfenyl, 2-cyano-1,1-dimentyl-ethoxycarbonyl,
bromobenzyloxy, carbamyl, formyl, and the like.
[0030] In all embodiments, the amphetamine moiety and the methamphetamine moiety are linked
to the first linking group in a symmetrical manner. In other words the two moieties
are linked to the first linking group from the same corresponding positions in the
respective moieties. In this way the moieties are disposed in the bivalent conjugate
such that they are essentially mirror images of one another except for the presence
of a methyl group in the methamphetamine moiety, instead of hydrogen, on the amine
group. In all embodiments, the moieties are linked from the respective phenyl groups
and, in all embodiments, from the 3-positions on the respective phenyl groups. For
homogeneous assays there should be sufficient competition between the respective antibodies
and the amphetamine moiety and methamphetamine moiety of the conjugate on the one
hand and the analyte amphetamine and methamphetamine on the other hand to produce
a reliable assay.
[0031] Furthermore, there should be sufficient inhibition of the label such as enzyme label
to achieve an accurate and sensitive assay.
[0032] In all embodiments, the amphetamine moiety and the methamphetamine moiety are each
stereospecific. By this is meant that the amphetamine moiety and the methamphetamine
moiety are the respective stereoisomers that are physiologically active.
[0033] The first linking group contains a functionality for linking to a second linking
group. The amphetamine moiety and the methamphetamine moiety are disposed in the first
linking group so that they are substantially equally spaced from the functionality
for linking to the second linking group. In some embodiments, the moieties are equally
spaced. By "substantially equally spaced" is meant that the spacing need only be sufficient
so that the moieties in the subsequent bivalent label conjugate are recognized by
their respective antibodies to the extent necessary to produce an accurate and sensitive
assay. Thus, in some circumstances the spacing from the functionality for linking
to the second linking group may not be equal as long as the above criteria are achieved.
In this manner, the distance of the amphetamine moiety and the methamphetamine moiety
from the point of linkage of the second linking group to the first linking group is
"approximately the same." For the present conjugates the spacing is about 10 Å to
about 80 Å, about 10 Å to about 70 Å, about 10 Å to about 60 Å, about 10 Å to about
50 Å, about 10 Å to about 40 Å, about 10 Å to about 30 Å, about 10 Å to about 20 Å,
about 12 Å to about 18 Å, about 12Å to about 16 Å.
[0034] The first linking group may comprise about 3 to about 15 atoms, or about 3 to about
10 atoms, not counting hydrogen or the functionality for linking to the second linking
group. The first linking group usually comprises a chain of 3, 4, 5, 6, 7, or 8 or
more atoms, e.g., from about 3 to about 8 atoms, about 3 to about 7 atoms, about 3
to about 6 atoms, about 4 to about 8 atoms, each independently selected from the group
normally consisting of carbon, oxygen, sulfur, nitrogen, halogen and phosphorous,
and so forth. The chain comprises a central atom, usually, but not necessarily, a
carbon atom, to which the functionality for linking to the second linking group is
attached. The number of heteroatoms in the first linking group, excluding the functionality
for linking to the second linking group, usually ranges from about 0 to about 6, usually
from about 2 to about 5. Although not required, the portions of the linking groups
that lie on either side of the central atom are, in some embodiments, substantially
symmetrical. In other words the atoms that extend away from the central atom to the
point of attachment of the amphetamine or methamphetamine moiety are the same for
each respective portion of the first linking group.
[0035] The first linking group may be aliphatic or aromatic. When heteroatoms are present,
oxygen will usually be present as oxo or ether bonded to carbon; sulfur is usually
present as a thioether or other functionality that corresponds to an analogous oxygen
functionality; nitrogen is usually present as nitro, nitroso or amino, normally bonded
to carbon; phosphorous is usually bonded to carbon, sulfur, oxygen or nitrogen, usually
as phosphonate and phosphate mono- or diester. Common functionalities in forming a
covalent bond between the linking group and the molecule to be conjugated, namely,
amphetamine and methamphetamine, include alkylamine, amidine, thioamide, ether, urea,
thiourea, guanidine, azo, thioether and carboxylate, sulfonate, and phosphate esters,
amides and thioesters.
[0036] For the most part, the functionality for linking to the second linking group may
be a non-oxocarbonyl group including nitrogen and sulfur analogs, a phosphate group,
an amino group, a thiol group, a hydroxy group, alkylating agent such as halo or tosylalkyl,
oxy (hydroxyl or the sulfur analog, mercapto) oxocarbonyl (e.g., aldehyde or ketone),
or active olefin such as a vinyl sulfone or α-,β-unsaturated ester, these functionalities
will be linked to amine groups, carboxyl groups, active olefins, alkylating agents,
e.g., bromoacetyl. Where an amine and carboxylic acid or its nitrogen derivative or
phosphoric acid are linked, amides, amidines and phosphoramides will be formed. Where
mercaptan and activated olefin are linked, thioethers will be formed. Where a mercaptan
and an alkylating agent are linked, thioethers will be formed. Where aldehyde and
an amine are linked under reducing conditions, an alkylamine will be formed. Where
a carboxylic acid or phosphate acid and an alcohol are linked, esters will be formed.
Various linking groups and linking functionalities are well known in the art; see,
for example,
Cautrecasas, J. Biol. Chem. (1970) 245:3059.
[0037] As mentioned above, a second linking group depends from the first linking group.
The second linking group provides for attachment of an attachable moiety such as,
for example, a poly(amino acid) or a non-poly(amino acid) label, to form a conjugate
in accordance with the present invention. Thus, the second linking group contains
a functionality for linking to an attachable moiety. The functionality for linking
to the attachable moiety may be, for example, any of the groups mentioned above for
the functionality for linking to second linking group, such as, for example, an amine
group, a carbonyl group, a hydroxy group, a thiol group, maleimide group, haloacetamide
and the like.
[0038] The second linking group may be simply a bond to an attachable moiety. The second
linking group may be a linking moiety similar in character to the first linking group.
An important consideration for the nature and length of the second linking group is
that it does not interfere with the recognition, by the respective antibodies, of
the amphetamine and methamphetamine moieties in the subsequent bivalent label conjugate
to the extent that an accurate and sensitive assay is not obtained. The second linking
group may comprise about 1 to about 30 atoms, usually, about 2 to about 25 atoms,
about 2 to about 20 atoms, about 4 to about 1 5 atoms, about 5 to about 10 atoms,
not counting hydrogen or a functionality for linking to the attachable moiety. The
second linking group usually comprises a chain of from about 1 to about 15 atoms,
about 2 to about 12 atoms, about 3 to about 10 atoms, about 4 to about 8 atoms, each
independently selected from the group normally consisting of carbon, oxygen, sulfur,
nitrogen, halogen and phosphorous, and so forth. The functionality for linking to
an attachable moiety is usually at the terminus of the chain of atoms although it
need not be. The number of heteroatoms in the second linking group, excluding the
functionality for linking to the attachable moiety, usually ranges from about 0 to
10, usually from about 2 to about 8, from about 3 to about 7.
[0039] Also included in the above compounds are salts thereof, particularly, salts involving
the amine group of the amphetamine and/or methamphetamine. In one embodiment the salts
are acid salts, i.e., salts formed with acids such as mineral acids, for example,
hydrochloric acid, hydrobromic acid, hydrofluoric acid, hydroiodic acid, phosphoric
acid, and the like, organic acids, for example, trifluoroacetic acid, tartaric acid,
acetic acid and so forth.
[0040] As mentioned above, one of the attachable moieties is a poly(amino acid). Various
protein types are included within the term "poly(amino acid)," both natural and synthetic.
These proteins include, for example, enzymes, albumins, serum proteins, e.g., globulins,
lipoproteins, and the like. The molecular weight of the poly(amino acids) will generally
be at least about 5,000 and have no upper limit, normally being less than 10,000,000,
and usually being not more than about 600,000. There will usually be different ranges
depending on the type of protein involved. With enzymes, the range will be from about
10,000 to 600,000, and more usually from about 10,000 to 300,000 molecular weight.
With antigens, the range will be from about 5,000 to 10,000,000, usually from about
20,000 to 600,000, and more usually from about 25,000 to 250,000 molecular weight.
There is usually at least about one amphetamine and methamphetamine analog group per
200,000 molecular weight, at least one per 50,000 molecular weight, at least one per
30,000 molecular weight. In the case of enzymes, the number of amphetamine and methamphetamine
analog groups is usually from about 1 to about 20, about 2 to about 15, about 3 to
about 12, or about 6 to about 10.
[0041] Enzymes of particular interest are redox enzymes, particularly dehydrogenases such
as glucose-6-phosphate dehydrogenase, lactate dehydrogenase, etc., and enzymes that
involve the production of hydrogen peroxide and the use of the hydrogen peroxide to
oxidize a dye precursor to a dye. Particular combinations include saccharide oxidases,
e.g., glucose and galactose oxidase, or heterocyclic oxidases, such as uricase and
xanthine oxidase, coupled with an enzyme which employs the hydrogen peroxide to oxidize
a dye precursor, that is, a peroxidase such as horse radish peroxidase, lactoperoxidase,
or microperoxidase.
When a single enzyme is used as a label, other enzymes may find use such as hydrolyses,
transferases, and oxidoreductases, preferably hydrolases such as alkaline phosphatase
and beta-galactosidase. Alternatively, luciferases may be used such as firefly luciferase
and bacterial luciferase.
[0042] Illustrative co-enzymes that find use include NAD[H], NADP[H], pyridoxal phosphate,
FAD[H], FMN[H], etc., usually coenzymes involving cycling reactions. See, for example,
U.S. Pat. No. 4,318,980.
[0043] The term "non-poly(amino acid) labels does not include enzyme labels. A non-poly(amino
acid) label may be a member of a signal producing system. The non-poly(amino acid)
label is capable of being detected directly or is detectable through a specific binding
reaction that produces a detectable signal. The non-poly(amino acid) labels generally
are radioisotopic, luminescent, particulate, polynucleotidic or the like. More particularly,
the label can be isotopic or non-isotopic, usually non-isotopic, and can be a polynucleotide
coding for a catalyst, promoter, dye, fluorescent molecule, chemiluminescent molecule,
coenzyme, enzyme substrate, radioactive group, a small organic molecule, amplifiable
polynucleotide sequence, a particle such as latex or carbon particle, metal sol, crystallite,
liposome, cell, etc., which may or may not be further labeled with a dye, catalyst
or other detectable group, and the like.
[0044] The signal producing system may have one or more compone nts, at least one component
being the label, whether poly(amino acid) or non-poly(amino acid). The signal producing
system generates a signal that relates to the presence of an amphetamine and/or methamphetamine
in a sample. The signal producing system includes all of the reagents required to
produce a measurable signal. Other components of the signal producing system may be
included in a developer solution and can include substrates, enhancers, activators,
chemiluminescent compounds, cofactors, inhibitors, scavengers, metal ions, specific
binding substances required for binding of signal generating substances, and the like.
Other components of the signal producing system may be coenzymes, substances that
react with enzymic products, other enzymes and catalysts, and the like. The signal
producing system provides a signal detectable by external means, by use of electromagnetic
radiation, desirably by visual examination. Exemplary signal-producing systems are
described in
U.S. Patent No. 5,508,178 (Rose, et al.).
[0045] As mentioned above, one aspect of the present invention concerns compounds of the
formula:
[0046]

wherein:
R1 is hydrogen protecting group;
R2 is hydrogen, lower alkyl, protecting group;
L1 is a linking group,
Y1 is a bond, a functional group or a linking group and is bonded to L1 at a point equidistant between the point of attachment to each of the phenyl groups,
Z1 is a poly(amino acid) moiety such as, for example, an enzyme, a non-poly(amino acid)
label moiety or a functional group; and
t" is 1 when Z1 is a functional group or a non-poly(amino acid) label moiety or, when Z1 is a poly(amino acid), t' is an integer between 1 and the molecular weight of a poly(amino
acid) moiety divided by about 500.
Also included within the above formula are salts of the above compounds.
[0047] By the term "lower alkyl" is meant a branched or unbranched saturated monovalent
hydrocarbon radical containing 1 to 10, usually, 1 to 5, carbon atoms, such as methyl,
ethyl, propyl, butyl and pentyl, and including the normal, secondary, tertiary, and
the like, forms thereof where appropriate.
[0048] Another embodiment of the present invention is directed to compounds of the formula:

wherein:
R1 and R2 are Independently H or a protecting group,
X and X' are independently O, S, or a bond;
D and D' are Independently alkylene or substituted alkylene;
V and V' are independently O, S, or a bond;
W is CH;
Y is NR3 wherein R3 is H or lower alkyl, O, S, a bond;
T is alkylene, -(C=O)alkylene, ethereal alkylene, acetamide or a bond;
Y' is NR3 wherein R3 is H or lower alkyl, O, S, or a bond;
T' is alkylene, -(C=O)alkylene, ethereal alkylene, acetamide or a bond; and
Z' is a poly(amino acid), a non-poly(amino acid) label moiety, H, halogen (Br, Cl,
F, I), NH2, acetamide, haloacetamide;
t" is 1 when Z' is a functional group or a non-poly(amino acid) label moiety or, when
Z' is a poly(amino acid), t" is an Integer between 1 and the molecular weight of a
poly(amino acid) moiety divided by about 500; with the proviso that X and X' have
approximately the same length, D and D' have approximately the same length, and V
and V' have approximately the same length;
Also included are salts of the above compounds.
[0049] "Approximately the same length" means that the lengths of the moieties in question
are such that the amphetamine moiety and the methamphetamine moiety are disposed so
that they are substantially equally spaced, or equally spaced, apart. In one embodiment,
the moieties are equally spaced.
[0050] "Alkylene" means a branched or unbranched saturated divalent hydrocarbone radical
containing 1 to 30 or more carbon atoms, such as methylene, ethylene, propylene 2-methylpropylene,
1,2-dimethylpropylene, pentylene, and the like. The term encompasses lower alkylene
(1 to 10 carbon atoms) and higher alkylene (11 to 30 carbon atoms).
[0051] "Ethereal alkylene" means alkylene having 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6,
1 to 5, 1 to 4, 1 to 3, 1 to 2, ether functions in the alkylene chain. An example,
by way of illustration and not limitation, is -[(CH
2)
a-O-(CH
2)
a]
c- wherein a and b are independently 1 to 5, 2 to 4, 1 to 3, 1 to 2, or 1, 2, 3, 4,
or 5 and wherein c is 1 to 15, 2 to 14, 3 to 13, 4 to 12, 5 to 11, 6 to 10, 7 to 9,
or 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, in particular, -[(CH
2)
a-O-(CH
2)
a]
c- wherein a and b are 2 and c is as defined above.
[0052] "Haloacetamide" means -XCH
2-CO-NH
c- wherein X is halogen (bromine, chlorine, fluorine, or iodine, usually, bromine or
chlorine).
[0053] "Substituted" means that a hydrogen atom of a molecule is replaced by another atom,
which may be a single atom such as a halogen, or heteroatom, or part of a group of
atoms forming, for example, alkyl groups, heteroatom substituted alkyl groups, cyclic
structures or heterocyclic structures.
[0054] Another embodiment of the present invention is a compound of the formula:

wherein:
R1' and R2 are independently H a protecting group,
X1' and X1" are S or O;
Z" is an enzyme; H, Br, Cl, Fl, I, NH2, acetamide, haloacetamide;
t"' is 1 when Z" is other than an enzyme and, when Z" is an enzyme, t"' is an integer
between 1 and the molecular weight of the enzyme divided by about 500; and
n, m, p, q, are each independently 1 to 5 and r and s are each independently 0 to
5.
The above formula also includes salts thereof.
[0055] Another embodiment of the present invention is a compound of the formula:

wherein:
Z" is an enzyme; and
t"' is an integer between 1 and the molecular weight of the enzyme divided by about
500.
[0056] The synthesis of representative examples of the above compounds is discussed herein
by way of illustration and not limitation. Other synthetic procedures will be suggested
to those skilled in the art in view of the disclosure herein. Other compounds within
the scope of the present invention may be prepared using suitable variants of the
reagents employed below.
[0057] Stereospecific amphetamine-methamphetamine bivalent hapten linked to an enzyme may
be synthesized, for example, by procedures outlined in Figure 1 and Figure 2. Protected
amphetamine derivative (
11) is reacted with protected methamphetamine derivative (
18) under conditions for the displacement of the bromine of derivative (
11) by the sulfur of derivative (
18) to give bivalent compound (
19). These conditions are generally basic conditions (pH about 8.0 to about 14.0). Suitable
bases include mono-, di-, and tri-alkyl amines such as, for example, diisopropylethyl
amine, ethyl amine, diethyl amine, triethyl amine, and the like. The reaction is usually
carried out in an organic solvent such as, for example, a ketone, e.g., acetone and
the like, an organic ether, e.g., ethyl ether, tetrahydrofuran (THF), dioxane, and
the like, an alcohol, e.g., methanol, ethanol, propanol, and the like. The reaction
temperature is usually about 0°C to about 50°C, more usually, about 10°C to about
30°C, preferably, ambient temperature. The reaction is carried out for a period of
about 10 minutes to about 3 hours or more, usually, about 30 minutes to about 60 minutes.
[0058] The keto functionality of compound (
19) is converted by reductive amination to an amine functionality to produce compound
(
20). The reaction is conducted in an organic solvent such as aqueous alcohol, Suitable
reagent include ammonium acetate and the like. A reducing agent such as a metal hydride,
for example, NaBH
3CN and the like may be employed. The reaction temperature is usually about 0°C to
about 50°C, more usually, about 10°C to about 30°C, preferably, ambient temperature.
The reaction is carried out for a period of about 1 hour to about 16 hours or more.
[0059] For the preparation of compound (
21), compound (
20) is reacted with an activated ester of bromoacetic acid, namely, the N-hydroxy succinimide
ester of bromoacetic acid in this example, under basic conditions, which include incorporating
into the reaction mixture an alkyl amine such as, for example, diisopropylethylamine,
ethylamine, triethyl amine, and the like. The reaction is conducted in an organic
solvent such as, for example, an ether, e.g., THF, Dioxane, diethyl ether and so forth.
The reaction is usually carried out at a temperature of about 0°C to about 50°C, more
usually, about 10°C to about 30°C, preferably, ambient temperature. The reaction is
carried out for a period of about 30 minutes to about 5 hours or more, usually, about
1 hour to about 3 hours or more.
[0060] The protecting group of compound (
21) may be removed under acidic conditions in an organic solvent to give compound (
22). In the example depicted, compound (
21) is treated with trifluoroacetic acid (TFA) in methylene chloride. In general, removal
of the protecting group is dependent on the nature of the protecting group. Suitable
conditions for removal of protecting groups are well known in the art and will not
be discussed in detail herein.
[0061] Compound (
20) may also be converted into compound (
23) by reaction with an activated ester of bromoacetylglycine, namely, the N-hydroxy
succinimide ester in the example shown in Figure 2. The reaction is carried out under
basic conditions with an organic solvent. The basic conditions include incorporating
into the reaction mixture an alkyl amine such as, for example, diisopropylethylamine,
ethylamine, triethyl amine, and the like. The reaction is conducted in an organic
solvent such as, for example, an ether, e.g., THF, dioxane, diethyl ether, and so
forth. The reaction is usually carried out at a temperature of about 0°C to about
50°C, more usually, about 10°C to about 30°C, preferably, ambient temperature. The
reaction time is a period of about 30 minutes to about 5 hours or more, usually, about
1 hour to about 3 hours or more. The protecting groups of compound (
23) may be removed as discussed above to produce compound (
24).
[0062] Any of the compounds discussed above may be purified by known techniques such as,
for example, dialysis, chromatography, HPLC, and combinations thereof.
[0063] Enzyme conjugates may be prepared from compounds in accordance with the present invention.
In general, functional groups suitable for attaching the compound to the enzyme are
usually an activated ester or alkylating agent when the amino acid(s) that are to
be conjugated on the enzyme have amino or hydroxyl groups and are usually alkylating
agents or the like when the amino acid(s) that are to be conjugated on the enzyme
comprise a sulfur atom such as, e.g., a cysteine. A large number of suitable functional
groups are available for attaching to amino groups and alcohols such as activated
esters including imidic esters, sulfonic esters and phosphate esters, activated nitrites,
aldehydes, ketones, alkylating agents and the like. Conjugation of haptens to proteins
using these and other attaching groups are well known in the art and are described
in reviews such as for example,
Maggio, E.T. "Enzyme-Immunoassay" (CRC Press, Boca Raton, Fla., 1980), Chapter 4, which contains an assortment of conjugation techniques; pages 81-88 of which are
incorporated herein by reference.
[0064] Following reaction of the enzyme with a compound such as discussed above to form
a conjugate, the product is then optionally purified as may be required. The purification
and characterization of poly(amino acid)-hapten conjugates has been described in detail
Maggio, et al.; "enzyme-immunoassay" (CRC Press, Boca Raton, Fla., 1980), Chapter
4, pages 86-88 of which are incorporated herein by reference. For example, if the conjugate is a
mutant G6PDH-hapten conjugate, the purification can be by dialysis against aqueous/organic
and aqueous solutions such as water/DMF or water, or by gel filtration chromatography
on supports such as Sephadex, and the like.
[0065] As mentioned above, the conjugation can involve binding of a hapten to a free thiol
group present on an amino acid side chain of the enzyme (e.g. cysteine). Such conjugation
involves alkylation of the thiol sulfur atom by treatment with an electrophilic compound
such as an alpha- or beta-unsaturated amide, ketone, ester, or the like, or an alkylating
agent such as a reactive halide, e.g., bromide, or sulfonate or the like or reaction
with an active disulfide such as a 2-nitro-4-carboxyphenyl disulfide. Specific examples
by way of illustration and not limitation include alpha-bromoamides, maleimides, vinyl
sulfones, alpha-iodoketones, and the like.
[0066] Conjugation reactions with enzymes can be affected by a number of factors. These
include, but are not confined to, pH, temperature, buffer, ionic strength, substances
which may protect the enzyme active site, amount and type of cosolvent, reaction time,
and activation chemistry. A range of pH values from about 5.0 to about 9.5 can usually
be used for conjugation reactions. These reactions are generally carried out at about
0 to about 40 degrees C, preferably about 4 to about 20 degrees C.
[0067] A number of buffers and salts, both alone and in combination, can be used for such
reactions. These include Tris, bicarbonate, phosphate, pyrophosphate, EDTA, KCI, NaCl,
and many others. The active site may be protected by substrates (i.e. glucose-6-phosphate
for glucose-6-phosphate dehydrogenase), cofactors (NAD
+, NADH, NADP
+, NADPH) and cofactor analogs (thio-NAD
+, thio-NADH, thio-NADP
+, or thio-NADPH), and compounds that react reversibly with lysine (i.e. pyridoxal)
to reduce deactivation of the enzyme during conjugation.
[0068] Cosolvents which may enhance hapten solubility include, but are not limited to, dimethylformamide,
carbitol, dimethyl sulfoxide, 1-Methyl-2-pyrrolidinone, and 1,3-Dimethyl-3,4,5,6-tetrahydro
2(1H)-pyrimidinone. These may be useful as about 1 to about 30% of the reaction volume.
Reactions can vary from about 15 minutes to many days, depending on the activation
chemistry. Carboxylic compounds may be activated to form esters with N-Hydroxysuccinimide
or its sulfo-analog, or to mixed anhydrides through reaction with carbitol chloroformate
or t-butylchloroformate, or may be coupled directly using carbodiimides such as EDAC.
For reaction with cysteine thiols on the enzyme, the hapten should contain a good
leaving group such as I, Br or tosyl; alternatively, the hapten can contain a thiol,
preferably activated with 2,2' dithiodipyridine or DTNB.
[0069] Another method of conjugation, described in
Rowley, G. L., D. Leung, and P. Singh (U.S. Pat. No. 4,220,722) involves modification of the enzyme with bromoacetyl containing reactants; the bromo
groups are subsequently reacted with thiol-containing haptens. The reactions of enzyme
with bromoacetyl modifier and the bromoacetyl enzyme with the thiolated hapten are
subject to the same reaction condition variables described above.
[0070] Enzyme conjugates may be prepared using compound (
22) or compound (24). For example, conjugates comprising glucose-6-phosphate dehydrogenase
may be prepared by procedures known in the art. These procedures generally involve
displacement of the bromine of compound (
22) or compound (
24) by a sulfur of a cysteine group of the enzyme. Since the enzyme has multiple cysteine
groups, more than one molecule of compound (
22) or compound (
24) usually becomes conjugated to the enzyme.
[0071] The label conjugates of the present invention may be employed in various assay formats.
Such assays usually involve reactions between binding partners such as an amphetamine
analyte and/or a methamphetamine analyte and a corresponding antibody or the binding
between an antibody and a corresponding binding partner such as a second antibody
that binds to the first antibody. Accordingly, the binding partner may be a protein,
which may be an antibody or an antigen. The binding partner may be a member of a specific
binding pair ("sbp member"), which is one of two different molecules, having an area
on the surface or in a cavity, which specifically binds to and is thereby defined
as complementary with a particular spatial and polar organization of the other molecule.
The members of the specific binding pair will usually be members of an immunological
pair such as antigen-antibody, although other specific binding pairs such as biotin-avidin,
hormones-hormone receptors, enzyme-substrate, nucleic acid duplexes, IgG-protein A,
polynucleotide pairs such as DNA-DNA, DNA-RNA, and the like are not immunological
pairs but are included within the scope of sbp member.
[0072] Accordingly, specific binding involves the specific recognition of one of two different
molecules for the other compared to substantially less recognition of other molecules.
On the other hand, non-specific binding involves non-covalent binding between molecules
that is relatively independent of specific surface structures. Non-specific binding
may result from several factors including hydrophobic interactions between molecules.
Preferred binding partners are antibodies.
[0073] The aforementioned reagents may be employed in all types of immunoassays to determine
the presence and/or amount of amphetamine analytes and/or methamphetamine analytes
in a sample suspected of containing such analytes. Such assays include, for example,
enzyme immunoassays, fluorescence polarization immunoassays, radioimmunoassay, particle
enhanced turbidimetric inhibition immunoassay and so forth.
[0074] One general group of immunoassays includes immunoassays using the labeled conjugates
of the invention with a limited concentration of antibody. Another group of immunoassays
involves the use of an excess of all of the principal reagents. Such assays include
two-site sandwich assays, e.g., immunoradiometric assays, immunofluorometric assays,
immunochemi-luminometric assays, ELISA assays, and so forth. Another group of immunoassays
are separation-free homogeneous assays in which the labeled reagents modulate the
label signal upon antigen-antibody binding reactions. Another group of assays includes
labeled antibody reagent limited competitive assays for hapten or antigen that avoid
the use of problematic labeled antigens or haptens. In this type of assay, it is important
that the solid phase immobilized analyte be present in a constant, limited amount.
The partition of a label between the immobilized analyte and free analyte depends
on the concentration of analyte in the sample.
[0075] The label conjugates of the invention may be employed with antibodies to amphetamine
and methamphetamine to conduct an immunoassay for the amphetamine and methamphetamine
analytes. The assays can be performed either without separation (homogeneous) or with
separation (heterogeneous) of any of the assay components or products. Homogeneous
immunoassays are exemplified by the EMIT® assay (Syva Company, San Jose, CA) disclosed
in
Rubenstein, et al., U.S. Patent No. 3,817,837, column 3, line 6 to column 6, line 64; immunofluorescence methods such as those
disclosed in
Ullman, et al., U.S. Patent No. 3,996,345, column 17, line 59, to column 23, line 25; enzyme channeling immunoassays ("ECIA")
such as those disclosed in
Maggio, et al., U.S. Patent No. 4,233,402, column 6, line 25 to column 9, line 63; the fluorescence polarization immunoassay
("FPIA") as disclosed, for example, in, among others,
U.S. Patent No. 5,354,693; and so forth.
[0079] The homogeneous or heterogeneous assays, particularly enzyme immunoassays and fluorescence
polarization immunoassays, are normally carried out in an aqueous buffered medium
at a moderate pH, generally that which provides optimum assay sensitivity. The aqueous
medium may be solely water or may include from 0 to about 40 volume percent of a cosolvent.
The pH for the medium will usually be in the range of about 4 to about 11, more usually
in the range of about 5 to about 10, and preferably in the range of about 6.5 to about
9.5. The pH will usually be a compromise between optimum binding of the binding members
of any specific binding pairs, the pH optimum for other reagents of the assay such
as members of the signal producing system, and so forth.
[0080] Various buffers may be used to achieve the desired pH and maintain the pH during
the determination. Illustrative buffers include borate, phosphate, carbonate, tris,
barbital and the like. The particular buffer employed is not critical to this invention,
but in an individual assay one or another buffer may be preferred. Various ancillary
materials may be employed in the method in accordance with the present invention.
For example, in addition to buffers the medium may comprise stabilizers for the medium
and for the reagents employed. Frequently, in addition to these additives, proteins
may be included, such as albumins; organic solvents such as formamide; quaternary
ammonium salts; polyanions such as dextran sulfate; surfactants, particularly non-ionic
surfactants; binding enhancers, e.g., polyalkylene glycols; or the like.
[0081] One or more incubation periods may be applied to the medium at one or more intervals
including any intervals between addition of various reagents mentioned above. The
medium is usually incubated at a temperature and for a time sufficient for binding
of various components of the reagents to occur. Moderate temperatures are normally
employed for carrying out the method and usually constant temperature, preferably,
room temperature, during the period of the measurement. Incubation temperatures normally
range from about 5° to about 99°C, usually from about 15°C to about 70°C, more usually
20°C to about 45°C. The time period for the incubation is about 0.2 seconds to about
6 hours, usually, from about 2 seconds to about 1 hour, more usually, about 1 to about
5 minutes. The time period depends on the temperature of the medium and the rate of
binding of the various reagents, which is determined by the association rate constant,
the concentration, the binding constant and dissociation rate constant. Temperatures
during measurements will generally range from about 10 to about 50°C, more usually
from about 15 to about 40□C.
[0082] The concentration of analyte that may be assayed generally varies from about 10
-5 to about 10
-17 M, more usually from about 10
-6 to about 10
-14 M. Considerations, such as whether the assay is qualitative, semi-quantitative or
quantitative (relative to the amount of analyte present in the sample), the particular
detection technique and the concentration of the analyte normally determine the concentrations
of the various reagents.
[0083] The concentration of analytes to be detected will generally vary from about 10
-5 to about 10
-17 M, more usually from about 10
-6 to about 10
-14 M. In general, a predetermined cut-off level is established for each analyte suspected
of being in a sample. The particular predetermined cut-off level generally is determined
on an analyte by analyte basis. Those skilled in the art are well aware of the factors
relating to the selection of predetermined cut-off levels. For example, for many drugs
of abuse, the cut-off levels are determined by SAMSA, an agency of the Department
of Health and Human Services. The nature of the signal producing system may be a consideration
in determining the predetermined cut-off levels of some analytes. Another consideration
is that the expected variation in concentration of the analytes that is of significance
should provide an accurately measurable signal difference.
[0084] The concentrations of the various reagents in the assay medium will generally be
determined by the concentration range of interest of the amphetamine and/or the methamphetamine
analytes. However, the final concentration of each of the reagents is normally determined
empirically to optimize the sensitivity of the assay over the range. That is, a variation
in concentration of analyte that is of significance should provide an accurately measurable
signal difference. Considerations such as the nature of the signal producing system
and the nature of, and predetermined cut-off levels for, the analytes normally determine
the concentrations of the various reagents.
[0085] While the order of addition may be varied widely, there will be certain preferences
depending on the nature of the assay. The simplest order of addition is to add all
the materials simultaneously and determine the effect that the assay medium has on
the signal as in a homogeneous assay. Alternatively, the reagents can be combined
sequentially. Optionally, an incubation step may be involved subsequent to each addition,
generally ranging from about 30 seconds to about 6 hours, more usually from about
1 minute to about 1 hour.
[0086] The following examples further describe the specific embodiments of the invention
by way of illustration and not limitation and are intended to describe and not to
limit the scope of the invention.
[0087] In a homogeneous assay after all of the reagents have been combined, the signal is
determined and related to the amount of analyte in the sample. For example, in an
EMIT assay for amphetamine and/or methamphetamine, a sample suspected of containing
amphetamine and/or methamphetamine analytes is combined in an aqueous medium either
simultaneously or sequentially with an enzyme conjugate of the invention and antibody
capable of recognizing amphetamine and antibody capable of recognizing methamphetamine
where the antibodies also bind to the respective amphetamine and methamphetamine moieties
of the enzyme conjugate prepared in accordance with the present invention. Generally,
a substrate for the enzyme is added, which results in the formation of a chromogenic
or fluorogenic product upon enzyme catalyzed reaction. Preferred enzymes are glucose-6-phosphate
dehydrogenase and alkaline phosphatase but other enzymes may be employed. The analytes
and the moieties of the enzyme conjugate compete for binding sites on the antibody.
The enzyme activity in the medium is then determined, usually by spectrophotometric
means, and is compared to the enzyme activity determined when calibrators or reference
samples are tested in which a known amount of the analytes is present. Typically,
the calibrators are tested in a manner similar to the testing of the sample suspected
of containing the analytes. The calibrators typically contain differing, but known,
concentrations of the analyte to be determined. Preferably, the concentration ranges
present in the calibrators span the range of suspected analyte concentrations in the
unknown samples.
[0088] The antibodies specific for amphetamine and specific for methamphetamine for use
in immunoassays can be monoclonal or polyclonal. Such antibodies can be prepared by
techniques that are well known in the art such as immunization of a host and collection
of sera (polyclonal) or by preparing continuous hybrid cell lines and collecting the
secreted protein (monoclonal) or by cloning and expressing nucleotide sequences or
mutagenized versions thereof coding at least for the amino acid sequences required
for specific binding of natural anti bodies.
[0089] Antibodies may include a complete immunoglobulin or fragment thereof, which immunoglobulins
include the various classes and isotypes, such as IgA, IgD, IgE, IgG1, IgG2a, IgG2b
and IgG3, IgM, etc. Fragments thereof may include Fab, Fv and F(ab')
2, Fab', and the like. In addition, aggregates, polymers, and conjugates of immunoglobulins
or their fragments can be used where appropriate so long as binding affinity for a
particular molecule is maintained.
[0090] Antiserum containing antibodies (polyclonal) is obtained by well-established techniques
involving immunization of an animal, such as a rabbit, guinea pig, or goat, with an
appropriate immunogen and obtaining antisera from the blood of the immunized animal
after an appropriate waiting period. State-of-the-art reviews are provided by
Parker, Radioimmunoassay of Biologically Active Compounds, Prentice-Hall (Englewood
Cliffs, N.J., U.S., 1976),
Butler, J. Immunol. Meth. 7: 1-24 (1975);
Broughton and Strong, Clin. Chem. 22: 726-732 (1976); and
Playfair, et al., Br. Med. Bull. 30: 24-31 (1974).
[0091] Antibodies can also be obtained by somatic cell hybridization techniques, such antibodies
being commonly referred to as monoclonal antibodies. Monoclonal antibodies may be
produced according to the standard techniques of
Köhler and Milstein, Nature 265:495-497, 1975. Reviews of monoclonal antibody techniques are found in
Lymphocyte Hybridomas, ed. Melchers, et al. Springer-Verlag (New York 1978),
Nature 266: 495 (1977),
Science 208: 692 (1980), and
Methods of Enzymology 73 (Part B): 3-46 (1981). Samples of an appropriate immunogen preparation are injected into an animal such
as a mouse and, after a sufficient time, the animal is sacrificed and spleen cells
obtained. Alternatively, the spleen cells of a non-immunized animal can be sensitized
to the immunogen
in vitro. The spleen cell chromosomes encoding the base sequences for the desired immunoglobulins
can be compressed by fusing the spleen cells, generally in the presence of a non-ionic
detergent, for example, polyethylene glycol, with a myeloma cell line. The resulting
cells, which include fused hybridomas, are allowed to grow in a selective medium,
such as HAT-medium, and the surviving immortalized cells are grown in such medium
using limiting dilution conditions. The cells are grown in a suitable container, e.g.,
microtiter wells, and the supernatant is screened for monoclonal antibodies having
the desired specificity.
[0092] Various techniques exist for enhancing yields of monoclonal antibodies, such as injection
of the hybridoma cells into the peritoneal cavity of a mammalian host, which accepts
the cells, and harvesting the ascites fluid. Where an insufficient amount of the monoclonal
antibody collects in the ascites fluid, the antibody is harvested from the blood of
the host. Alternatively, the cell producing the desired antibody can be grown in a
hollow fiber cell culture device or a spinner flask device, both of which are well
known in the art. Various conventional ways exist for isolation and purification of
the monoclonal antibodies from other proteins and other contaminants (see Köhler and
Milstein,
supra).
[0093] In another approach for the preparation of antibodies the sequence coding for antibody
binding sites can be excised from the chromosome DNA and inserted into a cloning vector,
which can be expressed in bacteria to produce recombinant proteins having the corresponding
antibody binding sites.
[0094] In general, antibodies can be purified by known techniques such as chromatography,
e.g., DEAE chromatography, ABx chromatography, and the like, filtration, and so forth.
[0095] The aforementioned assays may be carried out using mutant glucose-6-phosphate dehydrogenase
as the enzyme of the enzyme conjugate. This mutant enzyme is described in
U.S. Patent Nos. 6,090,567 and
6,033,890, the relevant disclosures of which are incorporated herein by reference. Furthermore,
the assay may be conducted using amphetamine antibodies and methamphetamine antibodies
as disclosed in
U.S. Patent Nos. 5,328,828 and
5,135,863, the relevant disclosures of which are incorporated herein by reference.
[0096] Heterogeneous assays usually involve one or more separation steps and can be competitive
or non-competitive. A variety of co mpetitive and non-competitive assay formats are
disclosed in
Davalian, et al., U.S. Patent No. 5,089,390, column 14, line 25 to column 15, line 9, incorporated herein by reference. In one
type of competitive assay a support having antibodies for amphetamine and for methamphetamine
bound thereto is contacted with a medium containing the sample and an enzyme conjugate
of the invention. After separating the support and the medium, the enzyme activity
of the support or the medium is determined by conventional techniques and related
to the amount of amphetamine and/or methamphetamine in the sample.
[0097] The support may be comprised of an organic or inorganic, solid or fluid, water insoluble
material, which may be transparent or partially transparent. The support can have
any of a number of shapes, such as particle, including bead, film, membrane, tube,
well, strip, rod, plate and the like. Depending on the type of assay, the support
may or may not be suspendable in the medium in which it is employed. Examples of suspendable
supports are polymeric materials such as latex, lipid bilayers or liposomes, oil droplets,
cells and hydrogels. Other support compositions include polymers, such as nitrocellulose,
cellulose acetate, poly (vinyl chloride), polyacrylamide, polyacrylate, polyethylene,
polypropylene, poly(4-methylbutene), polystyrene, polymethacrylate, poly(ethylene
terephthalate), nylon, poly(vinyl butyrate), etc.; either used by themselves or in
conjunction with other materials.
[0098] Binding of components to the surface of a support may be direct or indirect, covalent
or non-covalent and can be accomplished by well-known techniques, commonly available
in the literature, as discussed above. See, for example, "
Immobilized Enzymes," lchiro Chibata, Halsted Press, New York (1978) and
Cautrecasas, J. Biol. Chem., 245:3059 (1970). The surface of the support is usually polyfunctional or be capable of being polyfunctionalized
or be capable of binding to an sbp member, or the like, through covalent or specific
or non-specific non-covalent interactions. Such binding is indirect where non-covalent
interactions are used and is direct where covalent interactions are employed. A wide
variety of functional groups are available or can be incorporated. Functional groups
include carboxylic acids, aldehydes, amino groups, cyano groups, ethylene groups,
hydroxyl groups, mercapto groups and the like. The manner of linking a wide variety
of compounds to surfaces is well known and is amply illustrated in the literature
(see above).
[0099] Activation of the signal producing system depends on the nature of the signal producing
system members. For those members of a signal producing system that are activated
with light, the member is irradiated with light. For members of signal producing systems
that are on the surface of a particle, addition of a base may result in activation.
Other activation methods will be suggested to those skilled in the art in view of
the disclosures herein. For some signal producing systems, no agent for activation
is necessary such as those systems that involve a label that is a radioactive label,
an enzyme, and so forth. For enzyme systems addition of a substrate and/or a cofactor
may be necessary.
[0100] In certain embodiments a second enzyme may be employed in addition to the enzyme
of the enzyme conjugate. The enzymes of the pair of enzymes are related in that a
product of the first enzyme serves as a substrate for the second enzyme.
[0101] The examination for presence and amount of the signal also includes the detection
of the signal, which is generally merely a step in which the signal is read. The signal
is normally read using an instrument, the nature of which depends on the nature of
the signal. The instrument may be a spectrophotometer, fluorometer, absorption spectrometer,
luminometer, chemiluminometer, actinometer, photographic instrument, and the like.
The presence and amount of signal detected is related to the presence and amount of
the amphetamine and/or methamphetamine analytes present in a sample above the predetermined
cut-off level. Temperatures during measurements generally range from about 10° to
about 70°C, more usually from about 20° to about 45°C, more usually about 20° to about
25°C. In one approach standard curves are formed using known concentrations of the
analytes to be screened. As discussed above, calibrators and other controls may also
be used.
[0102] Another aspect of the present invention relates to kits useful for conveniently performing
an assay for the determination of amphetamine and/or methamphetamine analytes. The
kit comprises in packaged combination (i) an antibody for amphetamine, (ii) an antibody
for methamphetamine, and (iii) a compound of Formula IV wherein the compound comprises
an enzyme and wherein R
1' and R
2' are H.
[0103] To enhance the versatility of the subject invention, the kit reagents can be provided
in packaged combination, in the same or separate containers, in liquid or lyophilized
form so that the ratio of the reagents provides for substantial optimization of the
method and assay. The reagents may each be in separate containers or various reagents
can be combined in one or more containers depending on the cross-reactivity and stability
of the reagents.
[0104] The kit can further include other separately packaged reagents for conducting an
assay such as additional sbp members, ancillary reagents such as an ancillary enzyme
substrate, and so forth. The relative amounts of the various reagents In the kits
can be varied widely to provide for concentrations of the reagents that substantially
optimize the reactions that need to occur during the present method and further to
optimize substantially the sensitivity of the assay. Under appropriate circumstances
one or more of the reagents in the kit can be provided as a dry powder, usually lyophilized,
including excipients, which on dissolution will provide for a reagent solution having
the appropriate concentrations for performing a method or assay in accordance with
the present invention. The kit can further include a written description of a method
in accordance with the present invention as described above.
EXAMPLES
[0105] The invention is demonstrated further by the following illustrative examples. Parts
and percentages recited herein are by weight unless otherwise specified. Temperatures
are in degrees centigrade (°C).
[0106] Analytical thin layer chromatography (TLC) was the usual analysis method and performed
on Analtech Uniplate Silica Gel GF (0.25 mm) glass-backed plates using the specified
solvent. The spots on TLC were visualized by ultraviolet light (short and /or long
wave) and /or iodine vapors. Flash chromatography was carried out on Whatman silica
gel 60 Å (230-400 mesh). All chemicals were obtained from Sigma Chemical Company (St.
Louis, MO), Aldrich Chemical Company (St. Louis, MO), Fluka (Milwaukee, WI), and Lancaster
and used as received.
1H-NMR and
13C-NMR spectra routinely recorded on a Bruker Ultrashiel
™-400 (400 MHz) spectrometer (Bruker; Bellerica, MA01821). Chemical shifts were reported
in parts per million (ppm, □) and related to tetramethylsilane or with deuterated
solvent as internal reference. NMR abbreviations used are s (singlet), d (doublet),
and m (multiplet). Mass spectra were obtained at the Mass Spectrometry Laboratory,
University of California at Berkeley, Berkeley, California.
[0107] UV-visible absorption spectra were done on a HP 8452A diode array spectrophotometer.
Fluorescence measurements were done on a Spex fluorolog spectrophotometer or a Perkin
Elmer 650-40 spectrophotometer.
The following abbreviations have the meanings set forth below:
18-crown-6: 1,4,7,10,13,16-hexaoxacyclooctadecane
EtOH- ethanol
g - grams
Mel- iodomethane
ml- milliliter
mmol - millimolar
Pd/C- 10% Palladium on activated charcoal
DMF - dimethyl formamide
THF - tetrahydrofuran
NMR - nuclear magnetic resonance spectroscopy
MHz - megahertz
EDAC - 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (Sigma Chemical
Company)
MeOH - methanol
FAB-MS - fast atom bombardment - mass spectrometry
FAB-HRMS - fast atom bombardment - high resolution mass spectrometry EI-MS - electron
impact mass spectroscopy
EI-HRMS - - electron impact high resolution mass spectroscopy
DI water - deionized water
TNBS-2,4,6-trinitorbenzesulfonic acid
NHS - N-hydroxysuccinimic ester
tBoc2O - di-tert-butyldicarbonate
TFA - trifluoroacetic acid
Preparation of Antibodies
[0108] The antibodies used in the experiments herein were monoclonal antibodies prepared
as described in
U.S. Patent Nos. 5,328,828 and
5,135,863. In particular, see, for example, column 37, line 16, to column 39, line 55, of
U.S. Patent No. 5,135,863.
[0109] In general, the monoclonal antibodies were produced according to the standard techniques
of
Köhler and Milstein, Nature 265:495-497, 1975. Reviews of monoclonal antibody techniques are found in
Lymphocyte Hybridomas, ed. Melchers, et al. Springer-Verlag (New York 1978),
Nature 266: 495 (1977),
Science 208: 692 (1980), and
Methods of Enzymology 73 (Part B): 3-46 (1981). Samples of an appropriate immunogen preparation are injected into an animal such
as a mouse and, after a sufficient time, the animal is sacrificed and spleen cells
obtained. Alternatively, the spleen cells of an non-immunized animal can be sensitized
to the immunogen
in vitro. The spleen cell chromosomes encoding the base sequences for the desired immunoglobulins
can be compressed by fusing the spleen cells, generally in the presence of a non-ionic
detergent, for example, polyethylene glycol, with a myeloma cell line. The resulting
cells, which include fused hybridomas, are allowed to grow in a selective medium,
such as HAT-medium, and the surviving immortalized cells are grown in such medium
using limiting dilution conditions. The cells are grown in a suitable container, e.g.,
microtiter wells, and the supernatant is screened for monoclonal antibodies having
the desired specificity.
[0110] Various techniques exist for enhancing yields of monoclonal antibodies, such as injection
of the hybridoma cells into the peritoneal cavity of a mammalian host, which accepts
the cells, and harvesting the ascites fluid. Where an insufficient amount of the monoclonal
antibody collects in the ascites fluid, the antibody is harvested from the blood of
the host. Alternatively, the cell producing the desired antibody can be grown in a
hollow fiber cell culture device or a spinner flask device, both of which are well
known in the art. Various conventional ways exist for isolation and purification of
the monoclonal antibodies from other proteins and other contaminants (see Köhler and
Milstein,
supra).
Preparation of compound (11)
[0111] Compound (
11) was prepared starting with compound (
1) as described below (see also Figure 7).
Preparation of metaraminol (2)
[0112] To a solution of [-]-m-hydroxyphenyl propanolamine bitartrate salt (1) (40 g, 126
mmol) in water (60 ml) was added slowly of NH
4OH (60 ml). The mixture was stirred at room temperature for 0.5 hour. The mixture
was extracted with ethyl acetate (6 x 250 ml). The combined organic phase was washed
with water (30 ml) and dried over anhydrous MgSO
4. The organic solvent was filtered and the filtrate was evaporated by rotary evaporation
followed by high vacuum to dryness to give the desired product metaraminol (
2) (16.8 g, 79.7% yield). This product was used for next reaction without further purification.
Preparation of Compound (3)
[0113] To a stirred solution of metaraminol (
2) (16.8 g, 100.4 mmol) in chloroform (250 ml) was added slowly thionyl chloride (60
ml, 800 mmol) under argon. The reaction mixture was stirred for 0.5 hour and was heated
at 50°C for 45 minutes using an oil bath. The reaction mixture was cooled to room
temperature. The chloroform and most of excess thionyl chloride were removed by rotary
evaporation under high vacuum. After the evaporation, a crude solid residue was formed.
The solid residue was dissolved in MeOH (250 ml) and heated with charcoal (30 g) at
70°C by a water bath for 0.5 hour. The hot MeOH solution was filtered through a celite
pad (0.5 cm thickness) on a filtering funnel. The filtrate was evaporated by rotary
evaporation followed by high vacuum to dryness to give the desired product (
3) (19.0 g, 85.5% yield). This product was used for the next reaction without further
purification.
Preparation of Compound (4)
[0114] To a stirred solution of (
3) (19.0 g, 85.54 mmol) in EtOH (100 ml) was added 10% Pd/C (7.0 g) and the solution
was hydrogenated at a hydrogenator (parr) under 35 psi pressure of hydrogen for 16
hours. The ethanol solution was filtered through a celite pad (0.5 cm thickness) and
the celite pad was washed with EtOH (30 ml). The combined filtrates were evaporated
by rotary evaporation followed by high vacuum to dryness to give the desired product,
(2S)-3-(2-aminopropyl)phenol hydrochloride (
4) (16.1g, 100% yield).
1H-NMR (CD
3OD, 400MHz) □: 7.15 (m, 1H), 6.90 (m, 3H), 3.48 (m, 1H), 2.85 (m, 1H), 2.70 (m, 1H),
1.24 (d,
J=6.6 Hz, 3H). This product was used for next reaction without further purification.
Preparation of Compound (5)
[0115] To a stirred solution of (
4) (5 g, 26.64 mmol) in THF (150 ml) was added slowly of triethylamine (3.8 ml, 27.2
mmol). The reaction mixture was stirred at room temperature for 10 minutes. Acetic
anhydride (2.6 ml, 27.51 mmol) was added into the mixture followed by potassium carbonate
(3.68 g, 26.63 mmol). The reaction mixture was stirred at room temperature for 3 hours.
Water (50 ml) was added and most of THF was evaporated by rotary evaporation. The
aqueous phase was extracted with ethyl acetate (4 x 120 ml). The combined organic
phases were washed with water (40 ml) and dried over MgSO
4. The organic phase was evaporated to dryness by rotary evaporation and the residue
was dissolved in methanol (40 ml) and NH
4OH (10 ml). The solution was stirred at room temperature for 0.5 hour and most of
methanol was removed by rotary evaporation. Water (20 ml) was added and the aqueous
phase was extracted with ethyl acetate (4 x 50 ml). The combined extracts were washed
with water (15 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(4/1) as an eluent to give acetamine (
5) (3.90 g, 76% yield).
1H-NMR (CDCl
3, 400MHz) 0:7.91 (m, 1H; O
H), 7.12 (m, 1H), 6.77 (m, 2H), 6.68 (m, 1H), 5.61 (m, 1H, N
H), 4.28 (s, 1H), 2.81 (m, 1H), 2.66 (m, 1H), 1.98 (s, 3H), 1.13 (d,
J=6.5 Hz, 3H).
Preparation of Compound (6)
[0116] To a stirred solution of (
5) (2.45 g, 12.68 mmol) in DMF (80 ml) was added NaH (0.5g, 95%, 19.79 mmol) at 0°C.
The reaction mixture was stirred at room temperature for 45 minutes under argon. After
hydrogen evolution ceased, the reaction mixture was cooled to 0°C and dimethylthiocarbamoyl
chloride (2.35 g, 19.0 mmol) was added into the mixture. The reaction mixture was
stirred and heated at 45°C for 2 hours and allowed to cool to room temperature. Saturated
sodium chloride solution (50 ml) and water (30 ml) were added to the mixture. The
aqueous phase was extracted with ethyl acetate (3 x 100 ml) and the combined organic
phase was washed with saturated NaCl solution (50 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(9/1) as an eluent to give (
6) (2.9 g, 81.6% yield).
1H-NMR (CDCl
3, 400MHz) □: 7.30 (m, 1H), 7.05 (m, 1H), 6.90 (m, 2H), 5.36 (m, 1H, N
H), 4.30 (m, 1H), 3.44 (s, 3H), 3.34 (s, 3H), 2.79 (m, 2H), 1.93 (s, 3H), 1.09 (d,
J=6.4 Hz, 3H).
Preparation of Compound (7)
[0117] Neat compound (
6) (2.14g, 7.60 mmol) was stirred and heated under argon at 238-243°C in an oil bath
for 8 hours. The complete reaction was observed by thin layer chromatography (TLC)
(silica gel, ethyl acetate) by the disappearance of one spot and a new spot displayed
on TLC. The reaction was allowed to cool to room temperature. The oily residue was
purified by flash column chromatography (silica gel) using ethyl acetate as an eluent
to give (
7) (1.15 g, 53.7% yield).
1H-NMR (CDCl
3, 400MHz) □: 7.32-7.28 (m, 3H), 7.18 (m, 1H), 5.67 (m, 1H, N
H), 4.25 (m, 1H), 3.08 (s, 3H), 3.00 (s, 3H), 2.78 (m, 2H), 1.93 (s, 3H), 1.05 (d,
J=6.6 Hz, 3H);
13C-NMR (CDCl
3, 100 MHz) □: 170.09, 167.31, 139.09, 137.27, 133.71, 130.76, 129.11, 128.92, 46.02,
42.14, 37.30, 23.62, 20.08.
Preparation of Compound (8)
[0118] A mixture of (
7) (100 mg, 0.356 mmol) and KOH (400 mg, 7.13 mmol) in EtOH (9 ml) and water (6 ml)
was refluxed under argon for 4 hours. Most of ethanol was evaporated and water (14
ml) was added to the mixture. The aqueous solution was acidified with 6N HCl (pH about
3) and then extracted with ethyl acetate (4 x 40 ml). The combined extracts were dried
over MgSO
4, filtered, and evaporated to dryness by rotary evaporation. The residue was purified
by flash column chromatography (silica gel) using ethyl acetate/hexane (9/1) as an
eluent to give (
8) (42 mg, 56.3% yield). FAB-MS: MH
+ (210);
1H-NMR (CDCl
3, 400MHz) □: 7.15-7.07 (m, 3H), 6.93 (m, 1H), 5.57 (m, 1H, N
H), 4.20 (m, 1H), 3.42 (s, 1H, S
H), 2.75 (m, 1H), 2.58 (m, 1H), 1.91 (s, 3H), 1.07 (d,
J=6.6 Hz, 3H).
Preparation of Compound (9)
[0119] Compound (
8) (206 mg, 0.984 mmol) in 3N HCl (30 ml) was refluxed under argon for 48 hours. The
complete reaction was observed by thin layer chromatography (TLC) (silica gel, ethyl
acetate/hexane = 1/9). The reaction mixture was evaporated by rotary evaporation under
high vacuum to dryness. The residues were dissolved in water (5 ml). The aqueous solution
was frozen under argon and lyophilized to give (
9) (192 mg, 95% yield). FAB-MS: MH
+ (168);
1H-NMR (D
2O, 400MHz) □: 7.29-7.08 (m, 3H), 6.95 (m, 1H), 3.40 (m, 1H), 2.76 (m, 2H), 1.06 (d,
J=6.6 Hz, 3H);
13C-NMR (D
2O, 100 MHz) □: 137.78, 132.10, 130.32, 130.00, 128.12, 127.11, 49.53, 40.30, 18.07.
Preparation of Compound (10)
[0120] To a stirred solution of (
9) (192 mg, 0.942 mmol) in THF (12 ml) and water (6 ml) was added Di-
tert-butyl-dicarbonate (420 mg, 1.92 mmol) at 0 °C. The reaction mixture was stirred at
room temperature for 2 hours under argon. Water (14 ml) was added to the mixture and
most of THF was evaporated by rotary evaporation. The aqueous phase was extracted
with ethyl acetate (3 x 70 ml) and the combined organic phase was washed with saturated
NaCl solution (30 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness. The residue was purified
by flash column chromatography (silica gel) using ethyl acetate/hexane (1/4) as an
eluent to give (
10) (118 mg, 47% yield) and its disulfide dimer (
10a) (98 mg, 20% yield). (
10a): FAB-MS: (MH
+, 533);
1H-NMR(CDCl
3, 400MHz) □: 7.34-7.18 (m, 6H), 7.04-7.02 (m, 2H), 4.34 (m, 2H, N
H), 3.80 (m, 2H), 2.75 (m, 2H), 2.62 (m, 2H), 1.40 (s, 18H), 1.03 (d,
J=6.6 Hz, 6H). (
10): EI-MS
m/
z: 267 (M
+, 31), 211 (38), 194 (7), 151 (5), 144 (17), 123 (13), 88 (32), 57(100);
1H-NMR(CDCl
3, 400MHz) □: 7.15-7.08 (m, 3H), 6.95 (m, 1H), 4.38 (m, 1H, N
H), 3.85 (m, 1H), 3.41 (s, 1H, S
H), 2.76 (m, 1H), 2.62 (m, 1H), 1.42 (s, 9H), 1.06 (d,
J=6.6 Hz, 3H);
13C-NMR (CDCl
3, 100 MHz) □: 155.56, 139.84, 131.07, 130.72, 129.43, 127.68, 127.26, 79.62, 47.79,
43.17, 28.83, 20.52.
Preparation of monomer (10) from its disulfide dimer (10a)
[0121] To a stirred solution of dimer (
10a) (138 mg, 0.259 mmol) in THF (8 ml) and NaOAc/AcOH buffer solution (5 ml, pH=5.0)
was added Tris-(2-carboxyethyl) phosphine hydrochloride (76 mg, 0.265 mmol). The reaction
mixture was stirred at room temperature for 0.5 hour under argon. Most of THF was
evaporated by rotary evaporation and the aqueous phase was extracted with ethyl acetate
(3 x 30 ml). The combined organic phase was washed with saturated NaCl solution (20
ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness. The residue was purified
by flash column chromatography (silica gel) using ethyl acetate/hexane (1/4) as an
eluent to give (
10) (130 mg, 94% yield).
Preparation of Compound (11)
[0122] To a stirred solution of 1,3-dibromoacetone (144 mg, 0.667 mmol) in acetone (5 ml)
at 0°C under argon was added compound (
10) (20 mg, 0.0748 mmol) and diisopropyl ethyl amine (14 □I, 0.08 mmol). The reaction
mixture was stirred at 0°C for 45 minutes under argon. Acetone was evaporated to dryness
by rotary evaporation. The residue was purified by flash column chromatography (silica
gel) using ethyl acetate/hexane (1/4) as an eluent to give (
11) (20 mg, 66.5% yield). EI-MS
m/
z: 403(M
+, 52), 401 (M
+, 50), 347 (74), 345 (72), 330 (44), 328 (40), 260 (14), 258 (16), 144 (100), 88 (31),
57 (100);
1H-NMR(CDCl
3, 400MHz) □: 7.21-7.00 (m, 4H), 4.45 (m, 1H, N
H), 4.07 (s, 2H), 3.87 (brs, 3H), 2.80 (m, 1H), 2.65 (m, 1H), 1.41 (s, 9H), 1.05 (d,
J=6.4 Hz, 3H);
13C-NMR (CDCl
3, 100 MHz) □: 197.05, 155.53, 140.06, 133.82, 131.69, 129.67, 129.26, 128.53, 79.62,
47.68, 43.09, 41.52, 32.47, 28.83, 20.47.
Preparation of compound (18)
[0123] Compound (
2) was prepared starting with compound (
4) as described below (see also Figure 8).
Preparation of Compound (13)
[0124] To a stirred solution of (
4) (271 mg, 1.44 mmol) in CH
2Cl
2 (30 ml) was added KHCO
3 (144 mg, 1.44 mmol) followed by adding slowly triethylamine (0.8 ml, 5.73 mmol).
The reaction mixture was stirred at room temperature for 20 minutes. Trifluoroacetic
anhydride (0.6 ml, 4.24 mmol) was added into the mixture. The reaction mixture was
stirred at room temperature for 4 hours. Water (15 ml) was added and the organic phase
was separated. The aqueous phase was extracted with CH
2Cl
2 (4 x 30 ml). The combined organic phase were washed with 10% NaHCO
3 solution (30 ml) and dried over MgSO
4. The organic phase was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(2/3) as an eluent to give (
13) (274 mg, 77% yield). FAB-MS:MH
+ (248,100%);
1H-NMR(CDCl
3, 400MHz) □: 7.17-7.14 (m, 1H), 6.74-6.64 (m, 3H), 6.34 (m, 1H, N
H), 5.91 (m, 1H, O
H), 4.25 (m, 1H), 2.80-2.73 (m, 2H), 1.20 (d,
J=5.9 Hz, 3H). This reaction was repeated by using 10.9 g of (
4) and 8.6 g of (
13) was obtained. The
1H-NMR of (
13) in both lots is identical.
Preparation of Compound (14)
[0125] To a stirred solution of (
13) (1.65 g, 6:67 mmol) in DMF (30 ml) under argon was added NaH (332 mg, 95%, 13.14
mmol) at 0°C. The reaction mixture was stirred at 0°C for 10 minutes and at room temperature
for 45 minutes. After hydrogen evolution ceased, the reaction mixture was cooled to
0°C and dimethylthiocarbamoyl chloride (1.23 g, 9.95 mmol) was added. The reaction
mixture was stirred and heated at 40°C for 2 hours and allowed to cool to room temperature.
Saturated sodium chloride solution (15 ml) and water (35 ml) was added to the mixture.
The aqueous phase was extracted with ethyl acetate (4 x 80 ml) and the combined organic
phase were washed with saturated NaCl solution (50 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(3/7) as an eluent to give (
14) (1.12 g, 68% yield).
1H-NMR (CDCl
3, 400MHz) □: 7.25 (m, 1H), 7.00 (m, 2H), 6.90 (m, 1H), 6.81 (m, 1H, N
H), 4.20 (m, 1H), 3.36 (s, 3H), 3.24 (s, 3H), 2.85 (m, 1H), 2.72 (m, 1H), 1.15 (d,
J=6.7 Hz, 3H);
13C-NMR (CDCl
3, 100MHz) □: 187.93, 157.06, 154.51, 138.89, 129.60, 127.17, 124.19, 121.48, 47.91,
43.54, 41.79, 39.07, 19.56. HRFAB-MS Calcd for C
14H
18F
3N
2O
2S: 335.1042; Found: 335.1041.
Preparation of Compound (15)
[0126] Neat compound (
14) (1.0 g, 2.99 mmol) was stirred and heated under argon at 238-243°C in an oil bath
for 9 hours. The complete reaction was observed by thin layer chromatography (TLC)
(silica gel, ethyl acetate/hexane = 3/7) by the disappearance of (
14) and a new spot displayed at TLC which is more polar than (
14). The reaction was allowed to cool to room temperature. The oily residue was purified
by flash column chromatography (silica gel) using ethyl acetate/hexane = 3/7 as an
eluent to give (
15) (0.702 g, 70% yield).
1H-NMR (CDCl
3, 400MHz) □: 7.35-7.27 (m, 3H), 7.13 (m, 1H), 6.75 (m, 1H, N
H), 4.22 (m, 1H), 3.07 (s, 3H), 2.98 (s, 3H), 2.80-2.72 (m, 2H), 1.11 (d,
J=6.7 Hz, 3H);
13C-NMR (CDCl
3, 100MHz) □: 167.35, 156.8, 138.11, 137.16, 134.40, 130.67, 129.41, 128.92, 47.49,
41.56, 37.33, 19.57; HRFAB-MS Calcd for C
14H
18F
3N
2O
2S: 335.1042; Found: 335.1041.
Preparation of Compound (16)
[0127] To a stirred solution of (
15) (678 mg, 2.01 mmol) in THF (60 ml) under argon was added KH (231 mg, 5.75 mmol,
freed from protective mineral oil by washing with hexane three times followed by centrifugation).
The reaction mixture was stirred for 10 minutes and 18-crown-6 (230 mg) and Mel (2.0
mL, 32 mmol) was added to the mixture. The reaction mixture was allowed to stir at
room temperature for 2 hours and refluxed for 16 hours. Most of THF was removed by
rotary evaporation and ethyl acetate (60 ml) was added to the mixture followed by
cautiously adding of 10% aqueous HCl (10 ml) and water (20 ml). The organic phase
was separated and the aqueous phase was extracted with ethyl acetate (3 x 50 ml) and
the combined organic phase were washed with water (30 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(3/7) as an eluent to give (
16) (490 mg, 72% yield).
1H-NMR (CDCl
3,400MHz) □: 7.36-7.19 (m, 4H), 4.75, 4.20 (m, 1H), 3.08 (s, 3H), 2.98 (s, 3H), 2.90,
2.93 (s, 3H), 2.87-2.75 (m, 2H), 1.22 (m, 3H);
13C-NMR (CDCl
3, 100MHz) □: 167.20, 157.12, 138.60, 138.20, 136.65, 134.65, 134.41, 130.12, 129.63,
124.19, 54.58, 53.12, 41.17, 39.54, 37.33, 29.81, 28.46, 18.30, 16.98; HRFAB-MS Calcd
for C
15H
20F
3N
2O
2S: 349.1198; Found: 349.1194.
Preparation of Compound (17)
[0128] A mixture of (
16) (457 mg, 1.31 mmol) and KOH (1.1 g, 19.6 mmol) in EtOH (24 ml) and water (16 ml)
was refluxed under argon for 6 hours. The reaction mixture was allowed to cool to
room temperature. The aqueous solution was acidified with 1N HCl (pH about 3). Most
of ethanol was evaporated by rotary evaporation. The aqueous phase was frozen in dry
ice and lyophilized to give hydrochloride salt of (
17).
1H-NMR (D
2O, 400MHz) □: 7.40-7.00 (m, 4H), 3.40 (m, 1H), 2.93 (m, 1H), 2.72 (m, 1H), 2.62 (s,
3H), 1.17 (d,
J=6.5 Hz, 3H).
Preparation of Compound (18)
[0129] To a stirred solution of (
17) in THF (18 ml) and water (6 ml) was added di-tert-butyl-dicarbonate (571 mg, 2.62
mmol) and K
2CO
3 (387 mg, 2.80 mmol) at 0°C. The reaction mixture was stirred at room temperature
for 2 hours under argon. Water (15 ml) was added to the mixture and most of THF was
evaporated by rotary evaporation. The aqueous phase was extracted with ethyl acetate
(3 x 70 ml) and the combined organic phase was washed with saturated NaCl solution
(35 ml) and dried over MgSO
4. The organic solvent was filtered and evaporated to dryness. The residue was purified
by flash column chromatography (silica gel) using ethyl acetate/hexane (15/85) as
an eluent to give
(18) (295 mg, 84.2%) and its disulfide dimer
(18a) (40 mg, 11.4%).
(18): FAB-MS:(MH
+, 282);
1H-NMR (CDCl
3, 400MHz) □: 7.20-6.80 (m, 4H), 4.46-4.32 (m, 1H), 3.39 (s, 1H, S
H), 2.73-2.50 (m, 5H), 1.37-1.30 (m, 9H) 1.12 (m, 3H);
13C-NMR (CDCl
3, 100MHz) □: 155.87, 147.14, 140.45, 133.03, 130.93, 130.30, 129.37 127.67, 126.83,
85.59, 79.61, 52.81, 51.44, 40.77, 28.75, 28.59, 27.82, 18.89, 17.96.
Preparation of compound (19)
[0130] To a stirred solution of
(11) (87 mg, 0.216 mmol) in acetone (15 ml) was added a solution of
(18) (61 mg, 0.217 mmol) in acetone (1 ml) and diisopropylethyl amine (45uL, 0.258 mmol).
The reaction mixture was stirred at room temperature for 45 minutes. The complete
reaction was observed by the disappearance of compound
(11) on TLC. Acetone was evaporated to dryness. The residue was purified by flash column
chromatography (silica gel) using ethyl acetate/hexane (2/3) as an eluent to give
compound
(19) (110 mg, 84 %). EI-MS m/z: 602 (M
+, 18), 502 (62), 158 (56), 102 (100);
1H-NMR (CDCl
3, 400 MHz) □: 7.25-7.00 (m, 8H), 4.42-4.26 (m, 2H), 3.82(m, 4H), 2.78-2.55 (m, 8H),
1.41-1.24 (m, 18H), 1.11-1.02(m, 6H); FAB-HRMS Calculated (Calcd) for C
32H
46N
2O
5S
2Li (MLi
+): 609.3011; Found: 609.3008.
Preparation of compound (20)
[0131] To a stirred solution of
(19) (80 mg, 0.1327 mmol) (obtained as described above) in MeOH (15 ml) was added ammonium
acetate (194 mg, 2.51 mmol). The reaction mixture was stirred at room temperature
for 2 hours. Sodium cyanoborohydride (43 mg, 0.65 mmol) was added into the mixture.
The reaction mixture was stirred at room temperature for 16 hours. The complete reaction
was observed by the disappearance of compound
(19) on TLC and a more polar spot displayed (silica gel, ethyl acetate/hexane = 2/3).
Acetic acid (0.14 mL) was added to the reaction. The MeOH were evaporated to dryness
by rotary evaporation. The residue was purified by flash column chromatography (silica
gel) using MeOH/CH
2Cl
2 (1/9) as an eluent to give (20) (69 mg, 86% yield). EI-MS m/z: 604 (M
+, 51), 323 (76), 309 (45), 102 (100);
1H-NMR (CDCl
3, 400 MHz) □: 7.25-6.96 (m, 8H), 4.45-4.43 (m, 4H), 3.19(m, 5H), 2.67 (m, 8H), 1.42-1.20
(m, 18H), 1.13-1.05 (m, 6H); EI-HRMS Calcd for C
32H
49N
3O
4S
2(M
+): 603.3164; Found: 603.3177.
Preparation of compound (21)
[0132] To a stirred solution of
(20) (22 mg, 0.0364 mmol) (obtained as described above) in THF (4 ml) was added diisopropylethylamine
(50 µL, 0.286 mmol) and bromoacetic acid N-hydroxy succinimide (30 mg, 0.127 mmol)
at 0°C under argon. The reaction mixture was stirred at room temperature for 1.5 hours.
Water (5 ml) was added and most of the THF was removed by rotary evaporation. The
aqueous phase was extracted with CH
2Cl
2 (3 x 30 ml). The combined organic phase were washed with water (15 mL) and dried
over MgSO
4. The combined organic phase was filtered and evaporated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(2/3) as an eluent to give
(21) (19 mg, 72 % yield.) FAB-MS: (MLi
+, Br
79): 730; (MLi
+, Br
81) 732; Found: 730 (Br
79), 732 (Br
81);
1H-NMR (CDCl
3, 400 MHz) □: 7.22-7.00 (m, 8H), 4.65-4.20 (m, 3H), 3.90 (m, 1H), 3.68 (d,
J = 5.1 Hz, 2H), 3.34-3.30 (m, 2H), 3.19-3.15 (m, 2H), 2.85-2.61 (m, 8H), 1.41-1.26
(m, 18H), 1.12-1.05 (m, 6H); FAB-HRMS Calcd for C
34H
50BrN
3O
5S
2Li (MLi
+, Br
79): 730.2535; (MLi
+, Br
81): 732.2515; Found: 730.2540 (Br
79), 732.2543 (Br
81).
Preparation of compound (22)
[0133] To a solution of
(21) (18 mg, 0.0248 mmol) (obtained as described above) in CH
2Cl
2 (2 ml) was added trifluoroacetic acid (0.4 ml, 5.23 mmol). The reaction was stirred
at room temperature for 40 minutes. The excess of trifluoroacetic acid and the solvent
CH
2Cl
2 were removed by rotary evaporation and put in high vacuum. This gave the desired
product
(22) (18 mg, 96 % yield). FAB-MS: (MH
+, Br
79): 524; (MH
+, Br
81) 526; Found: 524 (Br
79), 526 (Br
81); FAB-HRMS Calcd for C
24H
35BrN
3OS
2 (MH
+, Br
79): 524.1404, (MH
+, Br
81): 526.1384; Found: 524.1400 (Br
79), 526.1394 (Br
81).
Preparation of compound (23)
[0134] To a stirred solution of
(20) (23 mg, 0.38 mmol) in THF (4 ml) was added diisopropylethylamine (50 µL, 0.286 mmol)
and bromoacetylglycine N-hydroxy succinimide (36 mg, 0.123 mmol) at 0°C under argon.
The reaction mixture was stirred at room temperature for 3 hours. Water (5 ml) was
added and most of the THF was removed by rotary evaporation. The aqueous phase was
extracted with CH
2Cl
2 (3 x 30 ml). The combined organic phase were washed with water (15 ml) and dried
over MgSO
4. The combined organic phase was filtered and concentrated to dryness by rotary evaporation.
The residue was purified by flash column chromatography (silica gel) using ethyl acetate/hexane
(3/2) as an eluent to give
(23) (6 mg, 20.2 % yield). FAB-MS: (MLi
+, Br
79): 787; (MLi
+, Br
81) 789; Found: 787 (Br
79), 789 (Br
81); FAB-HRMS Calcd for C
36H
53BrN
4O
6S
2Li (MLi
+, Br
79): 787.2749, (MLi
+, Br
81): 789.2729; Found: 787.2776 (Br
79), 789.2774 (Br
81).
Preparation of compound (24)
[0135] To a solution of
(23) (4 mg, 0.00512 mmol) (obtained as described above) in CH
2Cl
2 (2 mL) was added trifluoroacetic acid (0.3 mL, 3.92 mmol). The reaction was stirred
at room temperature for 60 minutes. The excess of trifluoroacetic acid and the solvent
CH
2Cl
2 were removed by rotary evaporation and further dried under high vacuum. This gave
the desired product
24 (4 mg, 96 % yield). FAB-MS: (MH
+, Br
79): 581; (MH
+, Br
81) 583; Found: 581 (Br
79), 583 (Br
81); FAB-HRMS Calcd for C
26H
38BrN
4O
2S
2 (MH
+, Br
79): 581.1819, (MH
+, Br
81): 583.1599; Found: 581.1612 (Br
79), 583.1582 (Br
81).
Preparation of enzyme conjugates using bivalent haptens (22) and (24)
[0136] Bivalent haptens
(22) and
(24), prepared as described above, were allowed to react with a glucose-6-phosphate dehydrogenase
(G6PDH) mutant enzyme to form the bivalent hapten/enzyme conjugate. In this mutant
enzyme, one amino acid in the primary amino acid sequence has been replaced with a
cysteine. The mutant enzyme was obtained by the procedure disclosed in
U.S. Patent Nos. 6,090,567 and
6,033,890, the relevant disclosures of which were incorporated hereinabove by reference. The
conjugation technique disclosed in
U.S. Patent Nos. 6,090,567 and
6,033,890 was then utilized to couple the bivalent hapten to the enzyme through a thioether
linkage. The preparation is described in
U.S. Patent No. 6,090,567 in particular at column 28, line 44, to column 43, line29, the disclosure of which
is incorporated herein by reference.
Inhibition of the bivalent hapten/G6PDH conjugates by amphetamine and methamphetamine
antibodies.
[0137] For a conjugate to have utility in EMIT assays, the antibody must inhibit the conjugate.
Therefore, conjugates prepared with bivalent haptens
(22) and
(24) (as described above) were incubated in the presence of amphetamine and methamphetamine
antibodies and tested for activity. The conditions and duration of incubation were
as follows:
An appropriate dilution of conjugate prepared with bivalent hapten (22) or (24) was mixed with either amphetamine or methamphetamine antibody, deionized water and
glucose-6-phosphate dehydrogenase substrates, at an appropriate pH and ionic strength,
in a final volume of 318 µL. After a 100-second incubation at 37°C, the enzyme activity
(ΔA/min at 340 nm) was measured. Control experiments with deionized water instead
of antibody established the uninhibited baseline activity, which was compared to the
activity in the presence of antibody to establish the degree of antibody dependent
conjugate inhibition. The results shown in Figure 1 demonstrate that when the enzyme
conjugate prepared with bivalent hapten (24) was allowed to interact with either amphetamine or methamphetamine antibody, there
was an antibody concentration dependent inhibition of the conjugate. Antibody concentration
dependent inhibition of enzyme conjugate prepared with bivalent hapten (22) was also observed (results not shown). Enzyme conjugate prepared with bivalent hapten
(24) was selected for further testing.
Utilization of the enzyme conjugate of bivalent hapten (24) to generate individual standard curves with amphetamine or methamphetamine
[0138] In order to test the presentation of the bivalent hapten
(24) in the enzyme conjugate to the antibody, competition experiments were performed between
the enzyme conjugate and either amphetamine or methamphetamine and the corresponding
antibody. The conditions and duration of incubation were as follows:
[0139] Methamphetamine calibrator solutions were prepared by diluting a stock solution of
methamphetamine (2000 ng/mL in urine) with methamphetamine negative urine, to final
concentrations of 1000 ng/mL, 600 ng/mL, 400 ng/mL, 200 ng/mL and 100 ng/mL. Amphetamine
calibrator solutions were prepared by diluting a stock solution of amphetamine (2000
ng/mL in urine) with amphetamine negative urine, to final concentrations of 1000 ng/mL,
600 ng/mL, 400 ng/mL, 200 ng/mL and 100 ng/mL. In order to generate the standard curve
for amphetamine with amphetamine antibody, an appropriate volume of each amphetamine
calibrator was incubated with an appropriate dilution of amphetamine antibody for
300 sec at 37° C. Conjugate prepared with bivalent hapten
(24) was then added and after an additional incubation of 100 sec, the enzyme activity
(ΔA/min at 340 nm) was determined. Enzyme activities were normalized by subtracting
the enzyme activity observed when negative (0 ng/mL) calibrator was used as the sample,
from the enzyme activity observed when each calibrator solution was used as the sample.
Results were then plotted as enzyme activity in normalized units versus the concentration
of amphetamine calibrator used. The standard curve for methamphetamine calibrators
with methamphetamine antibody was generated in an analogous manner as that for amphetamine.
[0140] Figure 2 shows the standard curve for amphetamine with amphetamine antibody. Figure
3 shows the standard curve for methamphetamine and methamphetamine antibody. A drug
concentration dependent response can be seen clearly when the enzyme conjugate of
bivalent hapten
(24) was tested with either the amphetamine and corresponding antibody or the methamphetamine
and corresponding antibody.
Assay for amphetamine and methamphetamine
[0141] The enzyme conjugate of bivalent hapten
(24) in conjunction with a mixture of amphetamine and methamphetamine antibodies was employed
to detect the presence of either amphetamine or methamphetamine in a sample. The conditions
and duration of incubation were as follows:
[0142] Methamphetamine calibrator solutions were prepared by diluting a stock solution of
methamphetamine (2000 ng/mL in urine) with methamphetamine negative urine, to final
concentrations of 1000 ng/mL, 600 ng/mL, 400 ng/mL, 200 ng/mL and 100 ng/mL. Amphetamine
calibrator solutions were prepared by diluting a stock solution of amphetamine (2000
ng/mL in urine) with amphetamine negative urine, to final concentrations of 1000 ng/mL,
600 ng/mL, 400 ng/mL, 200 ng/mL and 100 ng/mL. An antibody reagent consisting of methamphetamine
antibody plus amphetamine antibody mixed in an appropriate ratio was prepared. In
order to generate the standard curve for amphetamine with the amphetamine plus methamphetamine
antibody reagent, an appropriate volume of each amphetamine calibrator was incubated
with an appropriate dilution of the antibody reagent for 300 sec at 37° C. Conjugate
prepared with bivalent hapten
(24) was then added and after an additional incubation of 100 sec, the enzyme activity
(ΔA/min at 340 nm) was determined. Enzyme activities were normalized by subtracting
the enzyme activity observed when negative (0 ng/mL) calibrator was used as the sample,
from the enzyme activity observed when each calibrator solution was used as the sample.
Methamphetamine calibrators were then tested with the amphetamine plus methamphetamine
antibody reagent in an analogous manner. Results were then plotted as enzyme activity
in normalized units versus the concentration of amphetamine or methamphetamine calibrator
used. Figure 4 shows that a combination of the enzyme conjugate and both amphetamine
and methamphetamine antibodies detected the presence of either amphetamine or methamphetamine
in a sample.
[0143] The above discussion includes certain theories as to mechanisms involved in the present
invention. These theories should not be construed to limit the present invention in
any way, since it has been demonstrated that the present invention achieves the results
described.